Coffee Extract Process
The manufacture of instant coffee begins with brewing coffee in highly
efficient extraction equipment. Hot water is passed through a series of
five to eight columns of ground coffee beans. The water first passes
through several "hot" cells (284-356°F), at least some of which operate
at higher-than-atmospheric pressure, for extraction of difficult
components like carbohydrates. It then passes through two or more "cold"
cells (about 212°F) for extraction of the more flavorful elements. The
extract is passed through a heat exchanger to cool it to about 40°F. By
the end of this cycle, the coffee extract contains 20-30% solids.
After
a filtering step, the brewed coffee is treated in one of several ways
to increase its concentration. The goal is to create an extract that is
about 40% solids. In some cases, the liquid is processed in a centrifuge
to separate out the lighter water from the heavier coffee extract.
Another technique is to remove water by evaporation before cooling the
hot, brewed extract. A third alternative is to cool the extract enough
to freeze water, and then mechanically separate the ice crystals from
the coffee concentrate.
Source: http://www.madehow.com/Volume-3/Instant-Coffee.html#ixzz10I2OdBOQ
